暂无摘要。

Staphylococcus aureus is considered to be an extracellular pathogen. However, survival of S.aureus within host cells may cause long-term colonization and clinical failure. Current treatments have poor efficacy in clearing intracellular bacteria. Antibody-antibiotic conjugates (AACs) is a novel strategy for eliminating intracellular bacteria. Herein, we use KRM-1657 as payload of AAC for the first time, and we conjugate it with anti S. aureus antibody via a dipeptide linker (Valine-Alanine) to obtain a novel AAC (ASAK-22). The ASAK-22 exhibits good in vitro pharmacokinetic properties and inhibitory activity against intracellular MRSA, with 100 μg/mL of ASAK-22 capable of eliminating intracellular MRSA to the detection limit. Furthermore, the in vivo results demonstrate that a single administration of ASAK-22 significantly reduces the bacterial burden in the bacteremia model, which is superior to the vancomycin treatment.

The immunogenicity of haptens determines the performance of the resultant antibody for small molecules. Rigidity is one of the basic physicochemical properties of haptens. However, few studies have investigated the effect of hapten rigidity on the strength of an immune response and overall antibody performance. Herein, we introduce three molecular descriptors that quantify hapten rigidity. By using of these descriptors, four rifamycin haptens with varied rigidity were designed. The structural and physicochemical feasibility of the designed haptens was then assessed by computational chemistry. Immunization demonstrated that the strength of induced immune responses, i.e., the titer and affinity of antiserum, was significantly increased with increased rigidity of haptens. Furthermore, molecular dynamic simulations demonstrated conformation constraint of rigid haptens contributed to the initial binding and activation of naïve B cells. Finally, a highly sensitive indirect competitive enzyme-linked immunosorbent assay was developed for detection of rifaximin, with an IC50 of 1.1 μg/L in buffer and a limit of detection of 0.2-11.3 μg/L in raw milk, river water, and soil samples. This work provides new insights into the effect of hapten rigidity on immunogenicity and offers new hapten design strategies for antibody discovery and vaccine development of small molecules.

OBJECTIVE: Rifamycins are a group of antibiotics with a wide antibacterial spectrum. Although the binding target of rifamycin has been well characterized, the mechanisms underlying the discrepant killing efficacy between gram-negative and gram-positive bacteria remain poorly understood. Using a high-throughput screen combined with targeted gene knockouts in the gram-negative model organism Escherichia coli, we established that rifampicin efficacy is strongly dependent on several cellular pathways, including iron acquisition, DNA repair, aerobic respiration, and carbon metabolism. In addition, we provide evidence that these pathways modulate rifampicin efficacy in a manner distinct from redox-related killing. Our findings provide insights into the mechanism of rifamycin efficacy and may aid in the development of new antimicrobial adjuvants.

UNASSIGNED: The increase in incidence of multidrug-resistant bacteria and the inadequacy of new antimicrobial drugs have led to a widespread outbreak of bacterial antimicrobial resistance. To discover new antibiotics, biodiversity, and novelty of culturable actinobacteria dwelled in soil of the Western Qinghai-Tibet Plateau were investigated. By integrating antibacterial assay with omics tools, Amycolatopsis sp. A133, a rare actinobacterial strain and its secondary metabolites were further studied.
UNASSIGNED: Culture-dependent method was used to obtain actinobacterial strains from two soil samples collected from Ali region in Qinghai-Tibet Plateau. The cultural extractions of representative strains were assayed against \"ESKAPE\" pathogens by paper-disk diffusion method and the double fluorescent protein reporter \"pDualrep2\" system. An Amycolatopsis strain coded as A133 was prioritized and its secondary metabolites were further analyzed and annotated by omics tools including antiSMASH and GNPS (Global Natural Social Molecular Networking). The predicted rifamycin analogs produced by Amycolatopsis sp. A133 were isolated and identified by chromatographic separation, such as Sephadex LH-20 and HPLC, and spectral analysis, such as NMR and UPLC-HRESI-MS/MS, respectively.
UNASSIGNED: A total of 406 actinobacteria strains affiliated to 36 genera in 17 families of 9 orders were isolated. Out of 152 representative strains, 63 isolates exhibited antagonistic activity against at least one of the tested pathogens. Among them, 7 positive strains were identified by the \"pDualrep2\" system as either an inhibitor of protein translation or DNA biosynthesis. The cultural broth of Amycolatopsis sp. A133 exhibited a broader antimicrobial activity and can induce expression of TurboRFP. The secondary metabolites produced by strain A133 was annotated as rifamycins and zampanolides by antiSMASH and GNPS analysis. Five members of rifamycins, including rifamycin W, protorifamycin I, rifamycin W-M1, proansamycin B, and rifamycin S, were purified and identified. Rifamycin W-M1, was found as a new member of the naturally occurring rifamycin group of antibiotics.
UNASSIGNED: Assisted by omics tools, the successful and highly efficient discovery of rifamycins, a group of clinically used antibiotics from actinobacteria in Ali area encouraged us to devote more energy to explore new antibiotics from the soils on the Western Tibetan Plateau.

The study assessed the occurrence and distribution of microbial community and antibiotic resistance genes (ARGs) in food waste, anaerobic digestate, and paddy soil samples, and revealed the potential hosts of ARGs and factors influencing their distribution. A total of 24 bacterial phyla were identified, of which 16 were shared by all samples, with Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria accounting for 65.9-92.3 % of the total bacterial community. Firmicutes was the most abundant bacteria in food waste and digestate samples, accounting for 33-83 % of the total microbial community. However, in paddy soil samples with digestate, Proteobacteria had the highest relative abundance of 38-60 %. Further, 22 ARGs were detected in food waste and digestate samples, with multidrug, macrolide-lincosamide-streptogramin (MLS), bacitracin, aminoglycoside, tetracycline, vancomycin, sulfonamide, and rifamycin resistance genes being the most abundant and shared by all samples. The highest total relative abundance of ARGs in food waste, digestate, and soil without and with digestate was detected in samples from January 2020, May 2020, October 2019, and May 2020, respectively. The MLS, vancomycin, tetracycline, aminoglycoside, and sulfonamide resistance genes had higher relative abundance in food waste and anaerobic digestate samples, whereas multidrug, bacteriocin, quinolone, and rifampin resistance genes were more abundant in paddy soil samples. Redundancy analysis demonstrated that aminoglycoside, tetracycline, sulfonamide, and rifamycin resistance genes were positively correlated with total ammonia nitrogen and pH of food waste and digestate samples. Vancomycin, multidrug, bacitracin, and fosmidomycin resistance genes had positive correlations with potassium, moisture, and organic matter in soil samples. The co-occurrence of ARG subtypes with bacterial genera was investigated using network analysis. Actinobacteria, Proteobacteria, Bacteroidetes, and Acidobacteria were identified as potential hosts of multidrug resistance genes.

Standard and proper antituberculosis (anti-TB) treatment is essential for patients with TB, and rifamycin antibiotics are key components of anti-TB therapy. Therapeutic drug monitoring (TDM) of rifamycin antibiotics can shorten the time to response and complete treatment of TB. Notably, antimicrobial activities of the major active metabolites of rifamycin are similar to those of their parent compounds. Thus, a rapid and simple assay was developed for simultaneous determination of rifamycin antibiotics and their major active metabolites in plasma to evaluate their impact on target peak concentrations. Here, the authors have developed and validated a method for simultaneous determination of rifamycin antibiotics and their active metabolites in human plasma using ultrahigh-performance liquid chromatography tandem mass spectrometry.
Analytical validation of the assay was performed in accordance with the bioanalytical method validation guidance for industry described by the US Food and Drug Administration and the guidelines for bioanalytical method validation described by the European Medicines Agency.
The drug concentration quantification method for rifamycin antibiotics, including rifampicin, rifabutin, and rifapentine, and their major active metabolites was validated. Significant differences in the proportions of active metabolites in rifamycin antibiotics may affect the redefinition of their effective concentration ranges in the plasma. The method developed herein is expected to redefine the ranges of \"true\" effective concentrations of rifamycin antibiotics (including parent compounds and their active metabolites).
The validated method can be successfully applied for high-throughput analysis of rifamycin antibiotics and their active metabolites for TDM in patients receiving anti-TB treatment regimens containing these antibiotics. Proportions of active metabolites in rifamycin antibiotics markedly varied among individuals. Depending on the clinical indications of patients, the therapeutic ranges for rifamycin antibiotics may be redefined.

Objective: To investigate the effects of rifaximin treatment outcomes on complications and 24-week survival rate in cirrhotic patients with refractory type ascites. Methods: A retrospective cohort study was conducted on 62 cases with refractory ascites, and were divided into rifaximin treatment group (42 cases) and control group (20 cases) according to the actual treatment conditions. Rifaximin treatment group patients were administered oral rifaximin-α 200 mg four times daily for 24 consecutive weeks, and the other treatments were basically the same in both groups. Fasting body weight, ascites, complications and survival rate between the two groups were observed. Measurement data of the two groups using t-test, Mann-Whitney U test, and repeated measures analysis of variance were compared. χ2 test or Fisher\'s exact test were used to compare the enumeration data between the two groups. Kaplan-meier survival analysis was used to compare the survival rates. Results: At 24-week of rifaximin treatment, patients average body weight was reduced by 3.2 kg and the average ascites depth was reduced by 4.5 cm with B-ultrasound measurement, while in the control group at 24-week, the average body weight was reduced by 1.1 kg and the average ascites depth was reduced by 2.1 cm with B-ultrasound measurement, and the differences between the two groups were statistically significant (F=4.972, P=0.035; F=5.288, P=0.027). Hepatic encephalopathy incidence of grade II or above, hospitalization rates due to exacerbation of ascites, and spontaneous bacterial peritonitis were significantly lower in the rifaximin treatment group than those in the control group (2.4% vs. 20.0%, χ2=5.295, P=0.021; 11.9% vs. 50.0%, χ2=10.221, P=0.001; 7.1% vs. 25.0%, χ2=3.844, P=0.050). The 24-week survival rate was 83.3% in the rifaximin treatment group and 60.0% in the control group, P=0.039. Conclusion: Rifaximin treatment can significantly improve ascites symptoms, reduce the incidence of cirrhosis complications and improve the 24-week survival rate in cirrhotic patients with refractory type ascites.
目的： 探讨利福昔明对肝硬化难治型腹水患者的治疗效果、并发症和24周生存率的影响。 方法： 以回顾性队列研究的方法将62例难治型腹水患者根据实际治疗情况分为利福昔明治疗组42例和对照组20例。利福昔明组患者口服利福昔明α 200 mg、4次/d，连续24周。2组其他治疗基本相同。观察2组患者的空腹体质量、腹水情况、并发症和生存率。计量数据两组间比较采用t检验、Mann-Whitney U检验、重复测量方差分析；计数资料采用χ2检验或Fisher精确概率法进行组间比较；生存率比较采用Kaplan-Meier生存分析。 结果： 利福昔明治疗24周时患者平均体质量减轻3.2 kg，B超测量腹水深度平均减少4.5 cm，对照组24周时平均体质量减轻1.1 kg，B超测量腹水深度平均减少2.1 cm，两组比较差异均有统计学意义（F=4.972，P=0.035；F=5.288，P=0.027）。利福昔明治疗组患者Ⅱ级以上肝性脑病、因腹水加重而住院事件以及自发性细菌性腹膜炎的发生率均明显低于对照组（2.4%与20.0%，χ2=5.295，P=0.021；11.9%与50.0%，χ2=10.221，P=0.001；7.1%与25.0%，χ2=3.844，P=0.050）。利福昔明治疗组24周生存率83.3%，对照组24周生存率60.0%（P=0.039）。 结论： 利福昔明治疗肝硬化难治型腹水患者24周可显著改善腹水症状，降低了肝硬化并发症的发生率，提高24周生存率。.

The antibiotic options available for Mycobacterium abscessus (M. abscessus) infection are limited and no definitive therapeutic strategies have been formulated. The recent discovery that rifabutin is active against M. abscessus has raised interest in using rifabutin to treat this intractable disease. In this study, we evaluated the in vitro activity of rifabutin against 194 M. abscessus clinical isolates collected during 2012 January to 2017 December. As expected, rifabutin demonstrated considerably lower MICs against M. abscessus, with an MIC50 of 2 μg/mL and MIC90 of 4 μg/mL, respectively. Notably, the anti-M.abscessus activity was even stronger among clarithromycin-insusceptible strains. In addition, M. abscessus isolates with a rough morphotype were more sensitive to rifabutin compared with those forming smooth colonies when considered as a whole or in separate subspecies. Results from synergistic experiments revealed that the in vitro activity of rifabutin was significantly enhanced by the addition of amikacin, suggesting a promising strategy for M. abscessus infection combination treatment. Finally, five and three mutation patterns in rpoB and arr, respectively, were identified among the 194 strains through whole genome sequencing. However, none of them conferred rifabutin resistance. Our study is among the first to report the susceptibility of M. abscessus to rifabutin in vitro with a large amount of clinical isolates, suggesting that rifabutin is active, both alone and in combination, against M. abscessus and is worth considering as part of a combination treatment regimen for M. abscessus infections.

Rhodococcus equi is a zoonotic pathogen that can cause fatal disease in patients who are immunocompromised. At present, the epidemiology and pathogenic mechanisms of R. equi infection are not clear. This study characterized the genomes of 53 R. equi strains from different sources. Pan-genome analysis showed that all R. equi strains contained 11481 pan genes, including 3690 core genes and 602 ~ 1079 accessory genes. Functional annotation of pan genome focused on the genes related to basic lifestyle, such as the storage and expression of metabolic and genetic information. Phylogenetic analysis based on pan-genome showed that the R. equi strains were clustered into six clades, which was not directly related to the isolation location and host source. Also, a total of 84 virulence genes were predicted in 53 R. equi strains. These virulence factors can be divided into 20 categories related to substance metabolism, secreted protein and immune escape. Meanwhile, six antibiotic resistance genes (RbpA, tetA (33), erm (46), sul1, qacEdelta 1 and aadA9) were detected, and all strains carried RbpA related to rifamycin resistance. In addition, 28 plasmids were found in the 53 R. equi strains, belonging to Type-A (n = 14), Type-B (n = 8) and Type-N (n = 6), respectively. The genetic structures of the same type of plasmid were highly similar. In conclusion, R. equi strains show different genomic characteristics, virulence-related genes, potential drug resistance and virulence plasmid structures, which may be conducive to the evolution of its pathogenesis.